Process for producing precooked bacon slices

ABSTRACT

A process for producing precooked bacon slices comprising the steps of (a) conveying bacon slices through a spiral oven, (b) indirectly cooking the bacon slices in the spiral oven using a cooking medium which is circulated within the oven at a low rate sufficient to prevent the bacon slices from being displaced on the conveyor, and (c) adding steam to the cooking medium as necessary to at least reduce the percentage or substantially eliminate the presence of air in the cooking medium.

FIELD OF THE INVENTION

The present invention relates to processes for continuously cookingbacon slices to produce precooked bacon strips and other precookedsliced bacon products.

BACKGROUND OF THE INVENTION

Because of their thinness, the short cooking time required, and the highfat and water content of the raw product, bacon slices are among themost difficult products to cook consistently. The continuous baconcooking processes heretofore used in the industry have not been able toprovide precooked sliced bacon products having the same texture, bite,mouth feel, color, and appearance as pan-fried products cooked in thehome. Thus, a need presently exists for a significantly improvedcontinuous process and system capable of producing such precooked slicedbacon products. A need particularly exists for a process of this typewhich (a) will provide a production rate similar to the microwaveprocessing systems currently used in the art, (b) will take up lessfloor space in the processing facility, and (c) will eliminate or atleast greatly reduce the fire risk posed by other systems.

Heretofore, in the United States, precooked sliced bacon products havebeen predominantly produced using continuous microwave oven systems.Such microwave cooking processes have typically involved the steps of(a) preconditioning belly, shoulder, or back bacon or a formed bacon logto a temperature in the range of from about −4° to about 5° C.; (b)passing the preconditioned bacon through a Grote Slicer or similarslicing device; and then (c) conveying the sliced bacon through acontinuous microwave oven. As will be understood by those in the art,the Grote Slicer is typically positioned to place the bacon slicesdirectly on the oven conveyor as they are cut.

Unfortunately, the continuous microwave processes heretofore used forproducing precooked sliced bacon products have significant shortcomingsand disadvantages. For one thing, there are significant organalepticdifferences between the product produced by a continuous microwaveprocess versus a traditional home-fried product. This is due in largepart to the fact that the microwave energy has a more pronounced effecton the fat and water components of the bacon than on other parts. Thus,the microwave product has a significantly different texture, mouth feel,bite, appearance, and color. In addition, continuous microwave ovensystems can be as much as 70 feet or more in length and, thus, take up agreat deal of space in the processing facility.

As an alternative to continuous microwave cooking, precooked slicedbacon products have also been produced using continuous linearcirculating air oven systems. Unfortunately, however, the productsproduced in the linear circulating air oven systems have been even lesscrisp and lighter in color than the microwave products. In addition, thelinear circulating air systems have had a tendency to burn or blackenthe edges of the bacon slices and have also required an even greateramount of floor space to achieve throughputs approaching those of themicrowave systems. Further, because of the large amount of hot,flammable grease produced when cooking bacon, the fire risk presented bya circulating air oven is very high.

In addition, as will also be understood by those in the art, the generaltrend in the meat industry for achieving improvements in circulating aircooking processes has been toward the use of increasingly higher flowcirculation rates and impingement velocities. Unfortunately, however,the application of high velocity impingement air to the rather delicate,thinly sliced bacon product traveling through the oven causes theproduct to be displaced on (i.e., to be moved on or blown off of) theoven conveyor belt. Also, linear impingement oven systems would stilltake up a relatively large amount of space in the processing facilityand would present an even greater fire risk for bacon cooking.

SUMMARY OF THE INVENTION

The present invention provides a spiral oven process for preparingprecooked sliced bacon products which unexpectedly and surprisinglysatisfies the needs and alleviates the problems discussed above. Theinventive spiral oven process and system can produce a precooked slicedbacon product of generally any desired crispness and generally anydesired color ranging from light gold to very dark golden brown. Theinventive system also has a very small footprint and eliminates or atleast greatly reduces the fire risk posed by the prior art circulatingair oven systems. Moreover, the inventive bacon cooking process willproduce a consistent product which does not have burned or blackenedouter edges and is much closer than a microwaved product to home-friedbacon.

In one aspect, there is provided a process for continuously cookingbacon comprising the steps of: (a) placing bacon slices on a conveyor ofa spiral oven such that the conveyor carries the bacon slices throughthe spiral oven in a spiral pattern, the spiral oven having at least oneopening (e.g., for the conveyor) which is open to atmospheric conditionsoutside of the spiral oven; (b) indirectly cooking the bacon slices inthe spiral oven by contacting the bacon slices with a cooking mediumcirculating in the spiral oven at an average contacting temperature ofat least 325° F. and at a contact flow velocity which is sufficientlylow that the bacon slices will not be displaced on the conveyor whencontacted by the cooking medium; and (c) adding steam to the cookingmedium in a manner effective to maintain the cooking medium during step(b) such that a partial pressure of air which would otherwise be presentin the cooking medium without adding the steam in step (c) is reduced byat least 10%.

In another aspect, there is provided a process for continuously cookingbacon comprising the steps of: (a) placing bacon slices on a conveyor ofa spiral oven such that the conveyor carries the bacon slices upwardlyin the spiral oven in a spiral pattern, the spiral oven having an inletopening and an outlet opening for the conveyor wherein the inlet andoutlet openings are open to atmospheric conditions outside of the spiraloven; (b) indirectly cooking the bacon slices in the spiral oven bycontacting the bacon slices for a time in the range of from about 3 toabout 9 minutes with a cooking medium circulating in the spiral oven atan average contacting temperature in the range of from about 325° F. toabout 650° F. and at a nonimpinging contacting flow velocity which issufficiently low that the bacon slices will not be displaced on theconveyor when contacted by the cooking medium; and (c) adding steam tothe cooking medium in a manner effective to maintain the cooking mediumduring step (b) such that a partial pressure of air which wouldotherwise be present in said cooking medium without adding said steam instep (c) is reduced by at least 15%. When initially contacted by thecooking medium in the spiral oven, the bacon slices have a surfacetemperature which is sufficiently low to cause an amount of water fromthe cooking medium to initially condense on the bacon slices. Inaddition, the conveyor is an open conveyor such that fat dripping fromthose of the bacon slices traveling at higher elevations within thespiral oven will fall onto and baste those of the bacon slices travelingat lower elevations within the spiral oven.

In another aspect, there is provided a process for continuously cookingbacon comprising the steps of: (a) placing bacon slices on a conveyor ofa spiral oven such that the conveyor carries said bacon slices upwardlyin said spiral oven in a spiral pattern; (b) indirectly cooking thebacon slices in the spiral oven by contacting the bacon slices with acooking medium circulating in the spiral oven at an average contactingtemperature of at least 325° F. and at a contacting flow velocity whichis sufficiently low that the bacon slices will not be displaced on theconveyor when contacted by the cooking medium; (c) monitoring thecooking medium during step (b) using an analyzer of a type used fordetermining a relative humidity or dew point of air and for providinganalyzer result readings on a relative humidity percentage scale orother corresponding result scale; and (d) adding steam to the cookingmedium in a mainer effective to cause an analyzer result reading of orcorresponding to a value of at least 10% on the relative humiditypercentage scale to be maintained for the cooking medium during step(b).

Further aspects, features, and advantages of the present invention willbe apparent to those or ordinary skill in the art upon examining theaccompanying drawings and upon reading the following detaileddescription of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawing schematically illustrates an embodiment 2 of the inventivespiral oven process for continuously cooking bacon slices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment 2 of the inventive spiral oven process for continuouslycooking bacon slices is illustrated in the accompanying drawing. In theinventive process 2, raw bacon slices 4 are placed on the infeed section6 of the continuous conveyor belt 8 of a spiral oven 10. The raw baconslices 4 are preferably laid directly on the conveyor infeed section 6as they are cut from a bacon source (e.g., belly, shoulder, or backbacon, a formed bacon log, or other source) by a Grote Slicer or similarslicing device.

The spiral oven 10 used in the inventive process 2 preferably comprises:an oven housing 12 having a cooking chamber 15; a plurality of heatingelements 14 positioned in the upper portion of the housing 12 above thecooking chamber 15; a plurality of air flow cones or nozzles 16 providedin the upper portion of the housing below the heating elements 14 fordelivering the heated cooking medium into the cooking chamber 15; acirculation fan 18 provided in the housing 12 below the heating elements14; an exterior fan motor 20; an upper steam injection ring 22positioned between the circulation fan 18 and the heating elements 14;an optional lower steam injection ring 24 provided in the bottom of thecombustion chamber 15; a conveyor inlet opening 26 located at anelevation near the bottom of the cooking chamber 15; a conveyor outletopening 28 located at an elevational near the top of the cooking chamber15 beneath the air flow cones or nozzles 16; and a conveyor outletsection 30 which delivers the cooked sliced product 32 from the outlet28 of the spiral oven 10.

As is typical in spiral ovens, the conveyor belt 8 continuously conveysthe bacon slices 4 upwardly in the cooking chamber 15 in a spiralpattern as illustrated in the drawing. The belt 8 is preferably an openmesh belt (commercially available from Ashworth Brothers, Cambridgeinternational, and other manufacturers) or other type of open belt suchthat, as illustrated by basting drippage arrows 36, the fat which dripsfrom the products 4 traveling along the spiral flites 34 at succeedinglyhigher elevations within the oven housing 12 will fall onto and bastethe bacon slices 4 traveling along the flites 34 at lower elevations. Atthe same time, the cooking medium circulation fan 18 circulates the hotcooking medium within the oven housing 12 in a flow pattern 38 such thatthe fan 18 draws the cooking medium upwardly from the cooking chamber 15and blows the cooking medium through the upper heating elements 14 andthen downwardly via the air flow cones or nozzles 16 back into thecooking chamber 15.

The raw bacon slices 4 placed on the conveyor infeed section 6 can be ofany desired type, size, thickness, or shape. The slices 4 will typicallybe in the form of common breakfast strips which are approximately twoinches wide, approximately 10-12 inches long, and from about 1 to about5 mm thick. Wider slices can be provided, for example, by bonding twobellies together prior to slicing. The thickness of the bacon slices 4will typically be in the range of from about 1.2 to about 3.5 mm andwill more typically be in the range of from about 1.6 to about 3 mm. Asmentioned above, because of their relative thinness and the shortcooking time required, bacon slices are among the most difficultproducts to cook consistently.

In accordance with the inventive process 2, the bacon slices 4 areindirectly cooked as they travel upwardly through the cooking chamber 15of the spiral oven 10 by contacting the bacon slices with the heatedcooking medium which is circulated through the oven. In addition,another novel and unexpectedly beneficial aspect of the inventive baconcooking process is that the cooking medium will preferably be a highenthalpy, superheated vapor medium comprised of at least a high level ofwater vapor.

The high water vapor content of the cooking medium within the spiraloven 10 will preferably be produced and maintained by injecting steaminto the oven 10 as needed via the upper steam injection ring 22.Alternatively, or in addition, steam can be injected into the oven 10via the steam injection ring 24 within the bottom of the cooking chamber15. The steam can be saturated steam or superheated steam and willpreferably be superheated steam under pressure. The steam used in theinventive process will preferably be superheated steam provided to theinventive cooking system at a pressure of about 40 psig and atemperature of at least 265° F.

The amount of steam used in the inventive process will be an amounteffective to reduce the partial pressure of or substantially eliminatethe air which would otherwise be present in the “natural” cookingenvironment if no steam were injected into the spiral oven 10. Withoutsteam injection, the “natural” cooking environment would be comprised of(a) air, (b) volatile organics resulting from the bacon cooking process,and (c) an amount of water vapor derived from the water content of theraw bacon slices 4 and from the atmospheric humidity of the air. As willbe understood by those in the art, some additional water content in the“natural” cooking medium environment can also be derived from anymoisture which happens to remain on the conveyor belt 8 as a result ofthe continuous external belt cleaning process used during ovenoperation.

The reduction of air partial pressure and/or air content in theotherwise natural cooking environment results from the injection ofsteam and can also further result from the creation of a positivepressure condition with the oven 10. Depending, for example, on the sizeof the belt inlet and outlet openings 26 and 28 and upon the existenceof any other openings, the injection of a sufficient amount of steaminto the spiral oven 10 can, and preferably will, create a sufficientpositive pressure condition in the oven 10 to substantially preventoutside air from entering the oven openings during operation. Moreover,the design of the spiral oven 10 and the amount of steam injection canbe sufficient to create enough of an internal positive pressurecondition to cause some of the internal vapor to flow out of ovenopenings, thus resulting in a steady state condition whereinsubstantially all of the air has been removed and replaced with steam.

The amount of steam injected into the spiral oven 10 in the inventivebacon cooking process will preferably be an amount sufficient to reducethe partial pressure of air which would otherwise be present in the“natural” cooking environment by at least 10%. The amount of steaminjected into the spiral oven 10 will more preferably be an amountsufficient to reduce the partial pressure of air which would otherwisebe present by at least 15%, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, or at least 90%.The amount of steam injected into the spiral oven 10 will mostpreferably be an amount sufficient to replace substantially all of theair which would otherwise be present in the “natural” cookingenvironment.

In another surprising and unexpected aspect of the present invention, ithas been discovered that an extremely effective method for monitoringand controlling the injection of steam into the spiral oven 10 to targetand achieve any desired sliced bacon product characteristics is to use aVaisala dry cup dew point analyzer or other relative humidity and/or dewpoint monitoring device. The unexpected success obtained through the useof an instrument of this type for targeting and achieving substantiallyany desired product result in the present invention is particularlysurprising in view of the fact that the concept of “relative humidity”above the intended operational limit of such instruments (i.e., theboiling point of water) is, at best, ambiguous. Even more surprising isthe discovery that the resulting purported “percentage” or otherequivalent readings indicated on the relative humidity percentage scalesor corresponding scales (e.g., “dew point temperature”) of suchinstruments can be used in the inventive process to successfully controlsteam injection rates for achieving specific product results eventhough, in many and perhaps even most cases, most or all of the air inthe oven 10 will actually have been replaced with superheated steam.

The sensor for the Vaisala dry cup dew point transmitter or other devicecan be placed at generally any desired location within the spiral oven10. Although readings can be monitored at any desired location or at aplurality of points within the spiral oven 10, the analyzer readings forthe cooking medium will preferably be taken close to the actual cookingpoint, most preferably at a midpoint elevation in the cooking chamber 15and as close to the product as is reasonably feasible.

When using a Vaisala dry cup analyzer or similar instrument in theinventive process, the rate of steam addition to the spiral oven 10 willpreferably be controlled to maintain a targeted analyzer reading in therange of from at least 10% to 100%. In most cases, a targeted instrumentreading in the range of from about 15% to about 90%, more preferablyfrom about 20% to about 85%, will be used to control the rate of steaminjection to obtain the particular product characteristics desired. Onceagain, this control method has been found to be very effective for usein the inventive process even though the instrument may not actually be,and likely is not, measuring a true “relative humidity” of the heatedcooking medium.

Depending upon the desired operating ranges (e.g., the temperature rangeused and whether the environment is substantially oxygen free orcontains oxygen) and other factors, it will be understood that oxygenanalyzers or other types of instruments could be used to monitor andmaintain targeted conditions within the spiral oven 10 in at least somecases.

In further contrast to the industry trend toward using higher flowvelocities, even in spiral ovens, the inventive process alsounexpectedly provides surprising bacon cooking benefits by circulatingthe cooking medium within the spiral oven in a more gentle, convective,nonimpinging manner such that the cooking medium contacts the baconslices 4 at a flow velocity which is sufficiently low to prevent thebacon slices 4 from being displaced on (i.e., to prevent the baconslices 4 from being moved on or blown off of) the conveyor belt 8.

The contacting flow velocity within different regions of the cookingchamber 15 could vary depending upon the degree of doneness of theproduct at any given point. Although some heavier raw bacon productsentering the cooking chamber 15 could be contacted at a low flowvelocity of as much as 42 feet per second without displacing the producton the belt 8, the flow velocity, at least in the upper region of thecooking chamber 15, will preferably be lower in order not to displacethe lighter, cooked bacon product. Consequently, the circulation ratewithin at least the upper region of the cooking chamber 15 willpreferably be sufficiently low that the cooking medium will contact thebacon slices 4 at a flow velocity of not greater than 20 feet persecond. The contacting velocity in at least the upper portion of thecooking chamber 15 will more preferably not be greater than 10 feet persecond and will most preferably be only about 5.5 feet per second.

Spiral ovens adaptable for use in the inventive bacon cooking processare commercially available, for example, from Unitherm, Stein, Heat &Control, and C.F.S. The oven 10 will most preferably be a UnithermElectric Spiral Oven. Although such spiral ovens are typically operatedin other processes at much higher circulation rates, the spiral oven 10will preferably be operated at a much lower circulation rate in theinventive process 2, as already mentioned, in order to provide a moregentle, convective flow over the product. The fan speed of the UnithermElectric Spiral Oven, for example, will preferably be reduced to providea circulation rate of not more than 500 cubic feet per minute (CFM)within the oven 10.

The temperature and cooking time (i.e., belt speed) within the spiraloven 10 can be varied as desired to obtain generally any desired degreeof crispness and generally any desired color ranging from light gold todark golden brown. The average temperature of the cooking medium withinthe cooking chamber 15 will preferably be in the range of from about325° F. to about 650° F. or higher. Depending upon the degree ofcrispness and brownness required, the residence time of the product 4within the spiral oven cooking chamber 15 will typically be in the rangeof from about 3 to about 9 minutes.

In a preferred “high temperature” embodiment of the inventive method,the average temperature of the cooking medium will preferably be atleast 375° F. The average temperature of the cooking medium within thecooking chamber 15 in the “high temperature” embodiment will morepreferably be controlled in the range of from about 385° to 550° F. andwill most preferably be about 425° F. The residence/cooking time of theproduct within the spiral oven cooking chamber 15 in the “hightemperature” embodiment will preferably be in the range of from about 3to about 7 minutes and will most preferably be in the range of fromabout 4 to about 6 minutes. In addition, if a Vaisala dry cup analyzeror similar device is used to monitor the cooking medium within thecooking chamber 15, the amount of steam injected into the spiral oven 10in the “high temperature” embodiment will preferably be controlled tomaintain an analyzer reading which is or is equivalent to a value in therange of from about 15% to about 45%, most preferably in the range offrom about 20% to about 35%, on the purported “relative humidity”percentage scale of the Vaisala analyzer.

In an alternative “low temperature” embodiment, the average cookingmedium temperature will preferably be in the range of from about 325° F.to about 385° F. (most preferably about 350° F.), the analyzer readingfor the cooking medium will preferably be maintained in the range offrom about 45% to about 85% (most preferably about 75%), and the cookingtime will preferably be in the range of from about 6.5 to about 9minutes (most preferably about 8 minutes). The “low temperature”embodiment eliminates smoke and provides a product with little or no pitflavor notes.

The heating elements 14 employed in the spiral oven 10 can be thermaloil elements, steam elements, electric elements, or any other type ofelement capable of heating the circulating cooking medium within theoven 10 to the temperature desired. Because of the relatively highcooking temperatures typically preferred in the inventive process 2 andin order to provide a broad range of possible temperatures and results,the heating elements 14 will preferably be finned electrical heatingelements capable of heating the circulating cooking medium to a cookingtemperature of 650° F. or higher. In addition, to ensure that a highlyconsistent cooked product 32 is obtained and that none of the cookedproduct 32 is either undercooked or overcooked, those in the art willunderstand that the electrical heating elements 14 used in the spiraloven 10 will preferably be tightly controlled at the desired set pointusing a thyristor or similar device.

Because there is no need for the flow of makeup air into the spiral oven10 when employed in the inventive indirect cooking process 2, the inletopening 26 and the outlet opening 28 for the conveyor 8 can each be“choked” in order to (a) minimize the energy losses from the oven 10 tothe atmosphere, (b) further stabilize the cooking conditions therein,and (c) assist in establishing something of a positive pressurecondition in the spiral oven 10, when desired. Each of the inlet andoutlet openings 26 and 28 will preferably be only slightly wider thanthe oven belt 8 and will preferably be sufficiently limited in height toprovide not more than a 10 mm clearance, most preferably not more than a6 mm clearance, above the belt 8.

The high moisture content of the cooking medium, combined with therelatively high temperature within the oven 10, the gentle convectiveflow therein, and the natural basting provided by the upward spiral pathof the product through the oven 10, unexpectedly and surprisinglyprovides unique benefits and advantages which have not been provided bythe circulating air systems and other systems heretofore tried forcooking bacon slices. Even more surprisingly, these features of theinventive process unexpectedly combine to yield a cooked sliced baconproduct 32 which has much more of a pan-fried texture, bite, mouth feel,appearance, and color than the previously preferred products producedusing continuous microwave systems. The high moisture, high enthalpycooking medium employed in the inventive spiral oven process 2 alsofacilitates heat transfer into the sliced bacon product 4 and greatlyreduces or eliminates the fire risk posed by the prior circulating aircooking systems.

Moreover, the high water vapor content used and the othercharacteristics of the inventive spiral oven process 2 operate toenhance the browning process and protect the product during cooking sothat much more of a pan-fried color and a pan-fried crispness areobtained without burning or blackening the edges of the product. Thebacon product is preferably preconditioned prior to delivery to theslicer such that the bacon slices 4 deposited on the oven conveyor belt8 will have a low surface temperature, typically in the range of fromabout −6° to about 5° C. Because of the low initial surface temperatureof the raw bacon slices 4 and because of the high superheated watervapor content within the spiral oven 2, a small amount of water from thecooking medium initially condenses on the surface of the product 4,typically in micro droplet form, as the product enters the oven 10. Thecondensate which initially forms on the product surface heats rapidly,but it does so in conjunction with the fat on the product surface whichunexpectedly allows the fat to boil and to color the outer edges of theproduct without burning. Then, combined with the unexpected benefitprovided by the initial surface condensation effect, the fat drippagebasting regime within the oven 10 from each spiral flight 34 to the nextfurther operates to develop the color, crispness, and bite desired.

In addition, in an alternative embodiment of the inventive method, theraw bacon slices 4 can optionally be pretreated prior to entering thespiral oven cooking chamber 15 by contacting the raw slices 4 with dry(i.e., superheated) steam. The pretreating steam temperature willpreferably be about 250° F. The optional steam pretreatment begins themoisture crusting process and assists in producing a flatter slicedproduct.

EXAMPLE

A Grote Slicer is used to cut bacon slices directly onto the conveyorinfeed section 6 of a Unitherm Electric Spiral Oven 10 of the typeillustrated in the drawing. The bacon slices are each two inches wide,10 inches in length, and have a thickness of about 3 mm. The baconslices have an initial surface temperature of −6° C. The belt 8 of thespiral oven 2 is an open wire mesh belt which is 36 inches wide andwhich receives and conveys the raw bacon slices in a three lanearrangement across the belt at a total rate of 900 raw slices perminute. This is equivalent to a total feed rate of 5400 pounds per hourof raw sliced bacon.

The oven 10 utilizes finned electrical elements 14 which are operated toprovide an average cooking medium temperature within the cooking chamber15 of 425° F. The cooking medium within the oven cooking chamber 15 ismonitored using a Vaisala dry cup dew point analyzer. An analyzer valueof 24% for the cooking medium is maintained by the injection of 40 psigsuperheated steam at about 268° F. The injection of steam produces apositive pressure condition within the spiral oven 10 which is slightlyabove atmospheric pressure. The speed of the spiral conveyor 8 is set toprovide a cooking time of 5.5 minutes. The oven fan speed is set toprovide a cooking medium circulation rate within the oven 10 of 300cubic feet per minute.

The resulting cooked product has a crispness, appearance, and degree ofgolden brown color which are substantially the same as a bacon productwhich has been pan fried at 500° F. for 5 minutes (i.e., 2.5 minutes perside).

Thus, the present invention is well adapted to carry out the objectivesand attain the ends and advantages mentioned above as well as thoseinherent therein. While presently preferred embodiments have beendescribed for purposes of this disclosure, numerous changes andmodifications will be apparent to those of ordinary skill in the art.Such changes and modifications are encompassed within this invention asdefined by the claims.

1. A process for continuously cooking bacon comprising the steps of: (a)placing bacon slices on a conveyor of a spiral oven such that saidconveyor carries said bacon slices through said spiral oven in a spiralpattern, said spiral oven having at least one opening which is open toatmospheric conditions outside of said spiral oven; (b) indirectlycooking said bacon slices in said spiral oven by contacting said baconslices with a cooking medium circulating in said spiral oven at anaverage contacting temperature of at least 325° F. and at a contactingflow velocity which is sufficiently low that said bacon slices will notbe displaced on said conveyor when contacted by said cooking medium; and(c) adding steam to said cooking medium in a manner effective tomaintain said cooking medium during step (b) such that a partialpressure of air which would otherwise be present in said cooking mediumwithout adding said steam in step (c) is reduced by at least 10%.
 2. Theprocess of claim 1 wherein, when initially contacted by said cookingmedium in said spiral oven, said bacon slices have a surface temperaturewhich is sufficiently low to cause an amount of water from said cookingmedium to initially condense on said bacon slices, said amount of waterbeing effective to prevent burning and to promote browning of at leastan edge portion of each of said bacon slices.
 3. The process of claim 2wherein, when initially contacted by said cooking medium, said surfacetemperature of said bacon slices is in the range of from about −6° toabout 5° C.
 4. The process of claim 1 wherein said conveyor is an openconveyor which continuously carries said bacon slices upwardly in saidspiral pattern through said spiral oven such that fat dripping fromthose of said bacon slices traveling at higher elevations within saidspiral oven will fall onto those of said bacon slices traveling at lowerelevations within said spiral oven.
 5. The process of claim 1 whereinsaid average contacting temperature is at least 375° F. and said steamis added in step (c) in a manner effective to maintain said cookingmedium during step (b) such that said partial pressure of air whichwould otherwise be present in said cooking medium without adding saidsteam in step (c) is reduced by at least 20%.
 6. The process of claim 5wherein said steam is added in step (c) in a manner effective tomaintain a positive pressure condition in said oven during step (b). 7.The process of claim 1 wherein said steam added in step (c) issuperheated steam.
 8. The process of claim 1 wherein said spiral ovenhas choked inlet and outlet openings for said conveyor which have aheight extending not more than 10 mm above said conveyor.
 9. The processof claim 1 wherein said contacting flow velocity at which said baconslices are contacted by said cooking medium in step (b) is not greaterthan 20 feet per second.
 10. The process of claim 1 wherein saidcontacting flow velocity at which said bacon slices are contacted bysaid cooking medium in step (b) is not greater than 10 feet per second.11. The process of claim 1 wherein said steam is added in step (c) in amanner effective to maintain said cooking medium during step (b) suchthat said partial pressure of air which would otherwise be present insaid cooking medium without adding said steam in step (c) is reduced byat least 30%.
 12. The process of claim 1 wherein said cooking medium ismaintained at said average contacting temperature by circulating saidcooking medium over a plurality of finned electrical heating elements.13. The process of claim 1 further comprising the step, prior toindirectly cooking said bacon slices in said spiral oven, of contactingsaid bacon slices with superheated steam.
 14. A process for continuouslycooking bacon comprising the steps of: (a) placing bacon slices on aconveyor of a spiral oven such that said conveyor carries said baconslices upwardly in said spiral oven in a spiral pattern, said spiraloven having an inlet opening and an outlet opening for said conveyorwherein said inlet opening and said outlet opening are open toatmospheric conditions outside of said spiral oven; (b) indirectlycooking said bacon slices in said spiral oven by contacting said baconslices for a time in the range of from about 3 to about 9 minutes with acooking medium circulating in said spiral oven at an average contactingtemperature in the range of from about 325° to about 650° F. and at anonimpinging contacting flow velocity which is sufficiently low thatsaid bacon slices will not be displaced on said conveyor when contactedby said cooking medium; and (c) adding steam to said cooking medium in amanner effective to maintain said cooking medium during step (b) suchthat a partial pressure of air which would otherwise be present in saidcooking medium without adding said steam in step (c) is reduced by atleast 15%, wherein, when initially contracted by said cooking medium insaid spiral oven, said bacon slices have a surface temperature which issufficiently low to cause an amount of water from said cooking medium toinitially condense on said bacon slices and wherein said conveyor is anopen conveyor such that fat dripping from those of said bacon slicestraveling at higher elevations within said spiral oven will fall ontothose of said bacon slices traveling at lower elevations within saidspiral oven.
 15. The process of claim 14 wherein, when initiallycontacted by said cooking medium, said surface temperature of said baconslices is in the range of from about −6° to about 5° C.
 16. The processof claim 14 wherein said steam is added in step (c) in a mannereffective to maintain said cooking medium during step (b) such that saidpartial pressure of air which would otherwise be present in said cookingmedium without adding said steam in step (c) is reduced by at least 80%.17. The process of claim 14 wherein said steam added in step (c) issuperheated steam.
 18. A process for continuously cooking baconcomprising the steps of: (a) placing bacon slices on a conveyor of aspiral oven such that said conveyor carries said bacon slices upwardlyin said spiral oven in a spiral pattern; (b) indirectly cooking saidbacon slices in said spiral oven by contacting said bacon slices with acooking medium circulating in said spiral oven at an average contactingtemperature of at least 325° F. and at a contacting flow velocity whichis sufficiently low that said bacon slices will not be displaced on saidconveyor when contacted by said cooking medium; (c) monitoring saidcooking medium during step (b) using an analyzer of a type used fordetermining a relative humidity or dew point of air and for providinganalyzer result readings on a relative humidity percentage scale orother corresponding result scale; and (d) adding steam to said cookingmedium in a manner effective to cause an analyzer result reading of orcorresponding to a value of at least 10% on a relative humiditypercentage scale to be maintained for said cooking medium during step(b).
 19. The process of claim 18 wherein said steam is added in step (b)in a manner effective to cause an analyzer result reading of orcorresponding to a value of at least 15% on said relative humiditypercentage scale to be maintained for said cooking medium during step(b).
 20. The process of claim 18 wherein said steam is added in step (b)in a manner effective to cause an analyzer result reading of orcorresponding to a value of at least 20% on said relative humiditypercentage scale to be maintained for said cooking medium during step(b).
 21. The process of claim 19 wherein, when initially contacted bysaid cooking medium in said spiral oven, said bacon slices have asurface temperature which is sufficiently low to cause an amount ofwater from said cooking medium to initially condense on said baconslices, said amount of water being effective to prevent burning and topromote browning of at least an edge portion of each of said baconslices.
 22. The process of claim 19 wherein said conveyor is an openconveyor such that fat dripping from those of said bacon slicestraveling at higher elevations within said spiral oven will fall ontothose of said bacon slices traveling at lower elevations within saidspiral oven.
 23. The process of claim 18 wherein said average contactingtemperature is at least 375° F. and said steam is added in step (d) in amanner effective to cause an analyzer result reading of or correspondingto a value in the range of from about 15% to about 45% on said relativehumidity percentage scale to be maintained for said cooking mediumduring step (b).
 24. The process of claim 18 wherein said averagecontacting temperature is in the range of from about 385° F. to about550° F. and said steam is added in step (d) in a manner effective tocause an analyzer result reading of or corresponding to a value in therange of from about 20% to about 35% on said relative humiditypercentage scale to be maintained for said cooking medium during step(b).
 25. The process of claim 18 wherein said average contactingtemperature is in the range of from about 325° F. to about 385° F. andsaid steam is added in step (d) in a manner effective to cause ananalyzer result reading of or corresponding to a value in the range offrom about 45% to about 85% on said relative humidity percentage scaleto be maintained for said cooking medium during step (b).